The structural change of graphitization-controlled microporous carbon upon adsorption of H2O and N2

✍ Scribed by Takaomi Suzuki; Kasuh Takahiro; Katsumi Kaneko

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 500 KB
• Volume: 191
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(92)85590-7

✦ Synopsis

The partial graphitization of activated carbon fibers (ACFs) was controlled by heating at 1773-3173 K in Ar. The growth of graphitic crystallites was examined by high-resolution transmission electron microscopy and X-ray diffraction. The adsorption processes of H20 and N2 on the graphitization-controlled ACFs were investigated by use of the in situ X-ray diffraction. The adsorption of H20 at 303 K and N2 at 165 K led to shrinkage of the interlayer spacing, doo2, between the graphitic carbon layers. The shrinkage of more graphitized ACF is less remarkable than that of as-received ACF. The doo2 value decreased hardly until 40% of the fractional filling of H20, then it lowered markedly with the fractional filling. On the other hand, only less than 5% of the fractional filling decreased seriously the d0o2 value in the case of N 2 adsorption. The relationship between the molecular adsorption and the graphitic structural change was discussed on the basis of the adsorption process; N 2 molecules are at first adsorbed in the deep sites of the distorted slit-shaped micropores, while H20 molecules are firstly adsorbed near the entrance of the micropore with hydrophilic functional groups.